File extension xlsb is used by following file type(s):

File extension xlsb file type description:
Microsoft Excel 2007/2010 binary workbook file

The XLSB file extension is associated with Microsoft Excel, one of the most popular and powerful tool you can use to create format spreadsheets, graphs and much more.

The .xlsb files are used in Microsoft Excel 2007/2010 for Workbooks, spreadsheet document files saved in the binary format (BIFF12), instead of the new Open XML XLSX Excel workbook file format. The basic purpose of both files is the same, however the .xlsb files are a little larger and operate more efficiently in Microsoft Excel.

MIME: application/

that open xlsb files:
Microsoft Excel (Microsoft Windows)
Microsoft Office (Microsoft Windows)
Microsoft Office for Mac (Apple OS X)
Microsoft Office Mobile (Windows Mobile) Calc (multiplatform software)